In the field of image processing, processing a directly obtained image to obtain parameters related to an examined object is an important application, which generally involves an accurate modeling of the examined object. Specifically, an input region and an object region may be included in the obtained image, wherein the input region acts on the object region through a certain mechanism to obtain a corresponding output and/or an observable change in a certain state of the object region. This is equivalent to a response of the object region to the input, the response reflecting features of the object region. In the case where the input and the state change are known, a specific model can be constructed to obtain parameters reflecting the features of the object region.
For instance, in the processing of a medical image, it is usually required to process a series of images obtained by scanning to obtain physiological parameters of a related tissue or organ. Taking the blood perfusion imaging of the liver as an example, a selected slice is dynamically scanned after the intravenous bolus injection of contrast medium to obtain the time-density curve (TDC) of each pixel in this slice. Various perfusion parameters such as a hepatic artery perfusion (HAP), a hepatic portal perfusion (HPP) and a hepatic perfusion index (HPI), are calculated using different mathematical models according to the curve, and a perfusion image is formed through color level assignment to study the blood perfusion feature and the vascular characteristics of an organ and a lesion.